U.S. stocks edged lower on Friday and were on track for a weekly decline as investors reacted to an uncertain political environment stemming from President Donald Trump's firing of former FBI Director James Comey.

Meanwhile, a pair of economic reports, retail sales and consumer prices, rose in the latest month, albeit by a slower pace than had been expected, casting a mixed picture about the state of the economy.

The Dow Jones Industrial Average fell 41 points, or 0.2%, to 20,879. The S&P 500 slipped 4 points to 2,390, a decline of 0.2%. The Nasdaq Composite Index fell 1.7 point to 6,114, essentially unchanged on the day.

For the week so far, the Dow is looking at 0.6% drop and the S&P 500 at a 0.4% decline, each set to break a three-week string of weekly wins. The Nasdaq Composite is poised for a gain of 0.2%. That would mark the index's fourth straight weekly rise, albeit the smallest in the streak.

Major U.S. indexes continue to trade near record levels, and the CBOE Volatility index , a proxy for investor anxiety, has been trading near multidecade lows. Earlier this week, it closed at its lowest level in more than 23 years (http://www.marketwatch.com/story/is-this-the-day-wall-streets-fear-gauge-hits-rock-bottom-2017-05-08). The VIX fell 0.6% to 10.54 on Friday.

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"No one really knows what it means to have such a low VIX at a time of such high uncertainty, rising rates, high valuations, and corporate profits that aren't particularly strong," said Jonathan Angrist, chief investment officer of Cognios Capital. "It is very unusual."

The dominant story over the past few days has been the recent firing of Comey. While this is seen as having little direct impact on corporate profits or stock prices, prolonged uncertainty on this front could be a catalyst for greater investor anxiety and market declines. Friday morning, Trump tweeted that Comey should hope there are no "tapes" (http://www.marketwatch.com/story/trump-says-comey-should-hope-there-are-no-tapes-and-threatens-to-cancel-press-briefings-2017-05-12) of conversations between he and Trump, a statement he didn't elaborate on.

See also:Here's why stocks could rally if Trump heads for the exit (http://www.marketwatch.com/story/heres-why-stocks-could-rally-if-trump-heads-for-the-exit-2017-05-12)

"Who the FBI director is won't have an impact on markets, but it is part of a bigger puzzle," Angrist said. "There's a lot of political messiness, and that certainly leads to uncertainty and confusion in the market, and it suggests that, to me, we should have much higher volatility than we currently have. There's a tremendous amount of global uncertainty."

U.S. stocks finished with losses on Thursday (http://www.marketwatch.com/story/nasdaqs-record-run-on-the-line-as-snap-tumbles-after-results-2017-05-11), though well off session lows, led by declines for retail shares. Investors also grappled with the Comey firing which, among other things, suggested it might be even harder for Trump to push his economic agenda through congress, something experts say is necessary to justify the market's postelection rally.

Economic docket: Retail sales rose 0.4% in April (http://www.marketwatch.com/story/retail-sales-strengthen-in-april-brightening-economic-outlook-2017-05-12), according to the Commerce Department, below the 0.5% increase that had been forecast. Separately, consumer prices rose 0.2% (http://www.marketwatch.com/story/us-consumer-prices-rebound-in-april-2017-05-12) while core CPI was up 0.1%, a slighter increase than expected.

(http://www.marketwatch.com/story/jc-penney-options-traders-prep-for-an-unusually-wild-ride-after-earnings-report-2017-05-11)Tidewater Inc.(TDW) sank 7.6% after the oil services company said it expects to file for bankruptcy by May 17 (http://www.marketwatch.com/story/tidewaters-stock-plunges-after-announcing-bankruptcy-plan-2017-05-12).

In the same vein, Eli Lilly & Co. (LLY) picked up 0.3% before the open after saying a late-stage study of a migraine treatment met its primary goals (http://www.marketwatch.com/story/eli-lilly-reports-positive-results-in-trial-of-migraine-treatment-2017-05-12-791034).

Other markets: U.S. oil prices were unchanged in choppy trade on Friday, heading for a gain of more than 3% for the week. Investors remain hopeful that the Organization of the Petroleum Exporting Countries will extend a production-cut deal when it meets on May 25.

Also:Here's one thing that could scuttle an extension of OPEC's oil output cuts (http://www.marketwatch.com/story/heres-one-thing-that-could-scuttle-an-extension-of-opecs-oil-output-cuts-2017-05-12)

Asian stocks were mixed (http://www.marketwatch.com/story/asian-markets-pull-back-after-weak-earnings-in-us-2017-05-11), as some indexes retreated in step with U.S. stock losses, but Chinese equities gained. European stocks moved modestly higher (http://www.marketwatch.com/story/european-stocks-log-small-gains-as-vivendi-rallies-but-cartiers-parent-a-drag-2017-05-12).

Gold prices rose $5, or 0.4%, to $1,229.20 an ounce, while the dollar held steady.